JP6191826B2 - Method for producing grain-oriented electrical steel sheet with excellent magnetic properties - Google Patents
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Description
本発明は、変圧器の鉄心等に用いて好適な磁気特性に優れる方向性電磁鋼板の製造方法に関するものである。 The present invention relates to a method for producing a grain-oriented electrical steel sheet that is excellent in magnetic characteristics suitable for use in an iron core or the like of a transformer.
電磁鋼板は、変圧器やモーターの鉄心等として広く用いられる軟磁性材料である。中でも方向性電磁鋼板は、結晶方位がＧｏｓｓ方位と呼ばれる｛１１０｝＜００１＞方位に高度に集積しているため、磁束密度が高く、鉄損が低いという優れた磁気特性を有するため、主として変圧器の鉄心等に使用されている。 Electrical steel sheets are soft magnetic materials that are widely used as transformers and motor iron cores. Above all, grain oriented electrical steel sheets have excellent magnetic properties such as high magnetic flux density and low iron loss because the crystal orientation is highly integrated in the {110} <001> orientation called Goss orientation. Used in the iron core of containers.
結晶方位をＧｏｓｓ方位に高度に集積させる方法としては、インヒビタとよばれる析出物を利用する技術が知られている。上記インヒビタは、仕上焼鈍工程において、鋼中に微細に分散して析出し、結晶粒の粒成長を抑制し、Ｇｏｓｓ方位をもつ結晶粒のみを選択的に粒成長（以下、「二次再結晶」という）させる。 As a method for highly accumulating the crystal orientation in the Goss orientation, a technique using a precipitate called an inhibitor is known. In the finish annealing process, the inhibitor is finely dispersed and precipitated in the steel, suppresses crystal grain growth, and selectively grows only crystal grains having Goss orientation (hereinafter referred to as “secondary recrystallization”). ").
インヒビタの役割を果たす物質には幾つかあるが、中でもＡｌＮが最も工業的に広く利用されている。例えば、特許文献１には、鋼スラブに少量のＡｌを添加し、ＡｌＮを析出させてインヒビタとすることで、磁束密度を高める技術が開示されている。このＡｌＮをインヒビタとして利用する技術は、高磁束密度を得るのに極めて有効である。しかし、磁束密度をより高めるためには、仕上焼鈍で二次再結晶を起こさせる前の集合組織を適正化しておくことが必要である。すなわち、仕上焼鈍前の一次再結晶集合組織を適正化し、一次再結晶集合組織中に、二次再結晶を起こさせるＧｏｓｓ方位粒を十分な量形成させておくことが重要である。 There are several substances that act as inhibitors, but AlN is most widely used industrially. For example, Patent Document 1 discloses a technique for increasing the magnetic flux density by adding a small amount of Al to a steel slab and precipitating AlN to form an inhibitor. This technique of using AlN as an inhibitor is extremely effective for obtaining a high magnetic flux density. However, in order to further increase the magnetic flux density, it is necessary to optimize the texture before the secondary recrystallization is caused by finish annealing. That is, it is important to optimize the primary recrystallization texture before finish annealing and to form a sufficient amount of Goss orientation grains that cause secondary recrystallization in the primary recrystallization texture.
インヒビタとしてＡｌＮを用いる技術において、Ｇｏｓｓ方位粒の形成を促進する方法としては、冷間圧延工程で鋼板を加熱した状態で圧延する、あるいは、圧延パス間で鋼板を加熱・保持して時効処理を施す、いわゆる「温間圧延技術」が知られている。例えば、特許文献２には、複数のパスからなる圧下率が８１〜９５％の最終冷間圧延における複数のパス間において、鋼板に対して、５０〜３５０℃の温度範囲で１分以上の時効処理を、少なくとも１回以上施す技術が開示されている。また、特許文献３には、最終冷間圧延において、２００〜３００℃の温度での時効処理を少なくとも２パス以上施し、かつ、総圧下率５５％以上の段階で、噛込温度（噛み込み時の鋼板温度）を１１０〜１９０℃として２０〜３０％の圧延を行う技術が開示されている。 In the technique of using AlN as an inhibitor, as a method of promoting the formation of Goss orientation grains, the steel sheet is rolled in a cold rolling process, or the steel sheet is heated and held between rolling passes to perform an aging treatment. The so-called “warm rolling technique” is known. For example, in Patent Document 2, aging is performed for 1 minute or more in a temperature range of 50 to 350 ° C. with respect to a steel sheet between a plurality of passes in the final cold rolling with a reduction ratio of 81 to 95% consisting of a plurality of passes. A technique for performing the treatment at least once is disclosed. Further, in Patent Document 3, in the final cold rolling, an aging treatment at a temperature of 200 to 300 ° C. is performed at least two passes, and at a stage where the total rolling reduction is 55% or more, the biting temperature (at the time of biting) The steel plate temperature) is 110 to 190 ° C. and 20 to 30% rolling is disclosed.
上記のような温間圧延技術が有効である理由は、圧延によって導入された転移が固溶Ｃや炭化物で固着され、通常のすべり面以外のすべり面の活動を誘起されて剪断帯の形成が促進されて、剪断帯の内部にＧｏｓｓ方位粒の核が形成されるためであるとされている。このようにして形成されたＧｏｓｓ核は、一次再結晶焼鈍において再結晶し、二次再結晶の核となることで、仕上焼鈍後の二次再結晶粒が微細化し、鉄損の構成因子の一つである異常渦電流損を低減する。 The reason why the above-described warm rolling technique is effective is that the transition introduced by rolling is fixed by solute C or carbide, and the activity of slip surfaces other than the normal slip surface is induced to form a shear band. This is because it is promoted and nuclei of Goss-oriented grains are formed inside the shear zone. The Goss nuclei formed in this way are recrystallized in the primary recrystallization annealing and become the nuclei of secondary recrystallization, so that the secondary recrystallized grains after the finish annealing are refined and the iron loss is a constituent factor. One of the abnormal eddy current losses is reduced.
二次再結晶粒を微細化して鉄損を低減する技術としては、前述した温間圧延技術の他に、一次再結晶焼鈍の加熱過程を急速加熱する技術が知られている。例えば、特許文献４には、最終冷間圧延後の鋼板を７００℃以上の温度域へ８０℃／ｓ以上の昇温速度で急速加熱することで、二次再結晶粒を微細化し、鉄損を低減する技術が開示されている。また、同文献には、一次再結晶焼鈍の急速加熱技術と温間圧延技術を組み合わせることで、より鉄損特性が優れた方向性電磁鋼板を製造できることが開示されている。 As a technique for reducing the iron loss by refining the secondary recrystallized grains, a technique for rapidly heating the heating process of the primary recrystallization annealing is known in addition to the above-described warm rolling technique. For example, in Patent Document 4, the steel sheet after the final cold rolling is rapidly heated to a temperature range of 700 ° C. or higher at a rate of temperature increase of 80 ° C./s or more, thereby refining secondary recrystallized grains and iron loss. A technique for reducing the above is disclosed. In addition, this document discloses that a grain-oriented electrical steel sheet having more excellent iron loss characteristics can be manufactured by combining a rapid heating technique of primary recrystallization annealing and a warm rolling technique.
上記の一次再結晶焼鈍で急速加熱する技術は、短時間で再結晶温度以上の高温まで加熱することで、Ｇｏｓｓ方位よりも低温で再結晶を開始するＮＤ／／＜１１１＞方位粒の再結晶を抑制することで、Ｇｏｓｓ方位粒の再結晶を促進しようとするものである。 The technique of rapid heating by the above primary recrystallization annealing is to recrystallize ND // <111> oriented grains that start recrystallization at a temperature lower than the Goss orientation by heating to a temperature higher than the recrystallization temperature in a short time. By suppressing this, recrystallization of Goss oriented grains is promoted.
上述した技術を適用することで、高磁束密度でかつ低鉄損の方向性電磁鋼板を製造することが可能となった。しかし、昨今における省エネルギーに対する要求は一段と厳しくなり、上述した従来技術では、上記要求に応えることができる方向性電磁鋼板を安定して提供することが困難となってきている。 By applying the above-described technique, it is possible to produce a grain-oriented electrical steel sheet having a high magnetic flux density and a low iron loss. However, demands for energy saving in recent years have become more severe, and it has become difficult to stably provide a grain-oriented electrical steel sheet that can meet the above demands with the above-described conventional technology.
本発明は、上記の問題点に鑑みてなされたものであり、その目的は、従来よりも高磁束密度で低鉄損の方向性電磁鋼板を安定して製造する方法を提案することにある。 The present invention has been made in view of the above-described problems, and an object of the present invention is to propose a method for stably producing a grain-oriented electrical steel sheet having a higher magnetic flux density and a lower iron loss than before.
前述したように、冷間圧延における温間圧延技術と一次再結晶焼鈍における急速加熱技術は、いずれも、Ｇｏｓｓ方位核の形成とその再結晶を促進するものであり、それらの技術の相乗効果は大きいものがある。しかし、上記２つの技術は、二次再結晶粒の微細化を主たる目的とする技術であり、さらなる高磁束密度、低鉄損化を図るためには、二次再結晶粒の配向性をより高め、ヒステリシス損の低減することが有効であると考えられる。 As described above, both the warm rolling technology in cold rolling and the rapid heating technology in primary recrystallization annealing promote the formation of Goss orientation nuclei and their recrystallization. There is a big one. However, the above two technologies are technologies mainly aimed at miniaturization of secondary recrystallized grains, and in order to achieve further higher magnetic flux density and lower iron loss, the orientation of secondary recrystallized grains must be further increased. It is considered effective to increase and reduce the hysteresis loss.
上記課題を、集合組織の観点から達成するためには、一次再結晶集合組織におけるＮＤ／／＜１１１＞方位あるいはＮＤ／／＜４１１＞方位の集積度を向上することが重要となる。これらの方位は、二次再結晶時にＧｏｓｓ方位粒が蚕食していくマトリクスとなるので、二次再結晶におけるＧｏｓｓ方位粒の成長の優先度を高め、Ｇｏｓｓ方位に高度に集積した二次再結晶集合組織を得るのに重要であるからである。 In order to achieve the above-mentioned problem from the viewpoint of the texture, it is important to improve the degree of integration of the ND // <111> orientation or the ND // <411> orientation in the primary recrystallization texture. Since these orientations become a matrix in which the Goss orientation grains are phagocytosed during secondary recrystallization, the priority of growth of the Goss orientation grains in the secondary recrystallization is increased, and the secondary recrystallization highly accumulated in the Goss orientation. This is because it is important to obtain a texture.
一次再結晶集合組織において、ＮＤ／／＜１１１＞方位あるいはＮＤ／／＜４１１＞方位の集積度を向上させる技術としては、先述した特許文献３や４に開示されている、熱延板焼鈍の冷却速度を制御することで、冷間圧延前の鋼板中の固溶Ｃ，Ｎを低減する方法や、微細に析出させた炭化物を利用して、一次再結晶集合組織中のＮＤ／／＜１１１＞方位の強度を高める技術がある。しかし、これらの技術は、温間圧延技術や急速加熱技術を適用したときにＮＤ／／＜１１１＞方位が減少してしまうことへの対策としての意味合いが強く、集合組織を基本的に改善して磁気特性の向上を図ろうとするものではない。 In the primary recrystallization texture, as a technique for improving the degree of integration of the ND // <111> orientation or the ND // <411> orientation, as disclosed in Patent Documents 3 and 4 described above, By controlling the cooling rate, ND // <111 in the primary recrystallized texture using a method of reducing the solute C and N in the steel sheet before cold rolling and finely precipitated carbides. > There is a technique for increasing the strength of the orientation. However, these technologies have strong implications as countermeasures against the decrease in the ND // <111> orientation when applying warm rolling technology or rapid heating technology, and basically improve the texture. It is not intended to improve the magnetic characteristics.
そこで、発明者らは、最終冷間圧延における温間圧延条件に着目して詳細な検討を重ねた。その結果、複数パスからなる最終冷間圧延のパスを前半パスと最終板厚に近い後半パスとに分け、それぞれのパス前において適切な温度で時効処理を施すとともに、後半パスの噛込温度を最適化することで、一次再結晶集合組織におけるＧｏｓｓ方位強度を高め、ＮＤ／／＜４１１＞方位の強度も高めることができることを見出し、本発明を開発するに至った。 Therefore, the inventors repeated detailed examinations paying attention to the warm rolling conditions in the final cold rolling. As a result, the final cold rolling pass consisting of multiple passes is divided into a first half pass and a second half pass that is close to the final plate thickness, an aging treatment is performed at an appropriate temperature before each pass, and the biting temperature of the second half pass is set. It has been found that by optimizing, the Goss orientation strength in the primary recrystallization texture can be increased, and the strength of the ND // <411> orientation can be enhanced, and the present invention has been developed.
すなわち、本発明は、Ｃ：０．００２〜０．１０ｍａｓｓ％、Ｓｉ：２．５〜６．０ｍａｓｓ％、Ｍｎ：０．０１〜０．８ｍａｓｓ％、Ａｌ：０．０１０〜０．０５０ｍａｓｓ％、Ｎ：０．００３〜０．０２０ｍａｓｓ％を含有し、残部がＦｅおよび不可避的不純物からなる鋼スラブを熱間圧延し、熱延板焼鈍し、１回または中間焼鈍を挟む２回以上の冷間圧延し、脱炭焼鈍を兼ねた一次再結晶焼鈍し、鋼板表面にＭｇＯを主体とする焼鈍分離剤を塗布し、仕上焼鈍する一連の工程からなる方向性電磁鋼板の製造方法において、前記冷間圧延における最終冷間圧延を、２パス以上で総圧下率８０〜９５％で行い、かつ、総圧下率が６０％未満の範囲で少なくとも１パスを、１５０〜２５０℃×１分以上の時効処理を施した後、２０％以上の圧下率で圧延し、総圧下率が６０％以上の範囲で少なくとも１パスを、２５０〜３００℃×１分以上の時効処理を施した後、噛込温度を１５０℃以上として２０％以上の圧下率で圧延し、前記一次再結晶焼鈍の加熱過程における５００〜７００℃間の平均昇温速度を５０℃／ｓ以上とすることを特徴とする方向性電磁鋼板の製造方法を提案する。 That is, the present invention is C: 0.002-0.10 mass%, Si: 2.5-6.0 mass%, Mn: 0.01-0.8 mass%, Al: 0.010-0.050 mass%, N: 0.003 to 0.020 mass%, with the balance being Fe and inevitable impurities, hot-rolled steel slab, hot-rolled sheet annealed, cold once more than two times sandwiching intermediate or intermediate annealing In the method for producing a grain-oriented electrical steel sheet comprising a series of steps of rolling, primary recrystallization annealing also serving as decarburization annealing, applying an annealing separator mainly composed of MgO to the steel sheet surface, and finishing annealing, the cold The final cold rolling in the rolling is performed at a total reduction rate of 80 to 95% at 2 passes or more, and at least one pass is aging treatment at 150 to 250 ° C. for 1 minute or more in a range where the total reduction rate is less than 60%. 20% or more after applying After rolling at a rate of at least one pass in the range where the total rolling reduction is 60% or more, 250-300 ° C x 1 minute or more, and the biting temperature is 150 ° C or more, the rolling reduction is 20% or more. And a method for producing a grain-oriented electrical steel sheet, characterized in that an average rate of temperature increase between 500 and 700 ° C. in the heating process of primary recrystallization annealing is 50 ° C./s or more.
本発明の方向性電磁鋼板の製造方法に用いる上記鋼スラブは、上記成分組成に加えてさらに、Ｓ：０．００２〜０．０３ｍａｓｓ％およびＳｅ：０．００２〜０．０３％のうちから選ばれる１種または２種を含有することを特徴とする。 The steel slab used in the method for producing a grain-oriented electrical steel sheet of the present invention is selected from S: 0.002 to 0.03 mass% and Se: 0.002 to 0.03% in addition to the above component composition. It is characterized by containing 1 type or 2 types.
また、本発明の方向性電磁鋼板の製造方法に用いる上記鋼スラブは、上記成分組成に加えてさらに、Ｃｒ：０．０１〜０．５０ｍａｓｓ％、Ｃｕ：０．０１〜０．５０ｍａｓｓ％、Ｐ：０．００５〜０．５０ｍａｓｓ％、Ｎｉ：０．０１〜１．５０ｍａｓｓ％、Ｓｂ：０．００５〜０．５０ｍａｓｓ％、Ｓｎ：０．００５〜０．５０ｍａｓｓ％、Ｍｏ：０．００５〜０．１００ｍａｓｓ％、Ｂ：０．０００２〜０．００２５ｍａｓｓ％、Ｎｂ：０．００１０〜０．０１００ｍａｓｓ％およびＶ：０．００１〜０．０１ｍａｓｓ％のうちから選ばれる１種または２種以上を含有することを特徴とする。 Moreover, in addition to the said component composition, the said steel slab used for the manufacturing method of the grain-oriented electrical steel sheet of this invention is further Cr: 0.01-0.50mass%, Cu: 0.01-0.50mass%, P : 0.005-0.50 mass%, Ni: 0.01-1.50 mass%, Sb: 0.005-0.50 mass%, Sn: 0.005-0.50 mass%, Mo: 0.005-0 100% by mass, B: 0.0002 to 0.0025 mass%, Nb: 0.0010 to 0.0100 mass% and V: 0.001 to 0.01 mass%, or one or more selected from It is characterized by that.
本発明によれば、高磁束密度かつ低鉄損の方向性電磁鋼板を安定して提供することが可能となる。 According to the present invention, a grain-oriented electrical steel sheet having a high magnetic flux density and a low iron loss can be stably provided.
まず、本発明を開発するに至った実験について説明する。
Ｃ：０．０７ｍａｓｓ％、Ｓｉ：３．３ｍａｓｓ％、Ｍｎ：０．０６ｍａｓｓ％、Ａｌ：０．０２４ｍａｓｓ％およびＮ：０．００８０ｍａｓｓ％を含有する鋼スラブを１４００℃に再加熱した後、熱間圧延して２．２ｍｍの板厚とし、１１００℃×６０秒の熱延板焼鈍を施した後、冷間圧延して板厚１．５ｍｍとし、１１２０℃×８０秒の中間焼鈍を施した後、２回目の冷間圧延で最終板厚が０．２３ｍｍの冷間圧延板とした。
ここで、上記２回目の冷間圧延（最終冷間圧延）は６パスとし、表１に示すパススケジュールで圧延した。さらに、２パス目と５パス目の圧延前に、鋼板をさまざまな温度に加熱して１０分間保持する時効処理を施し、１パス目、３パス目および４パス目の圧延前は、１００℃で１０分間保持する時効処理を施した。また、噛込温度（噛み込み時の鋼板温度）は、５パス目のみ１８０℃とし、それ以外のパスでは１００℃以下に冷却してから通板した。
First, the experiment that led to the development of the present invention will be described.
A steel slab containing C: 0.07 mass%, Si: 3.3 mass%, Mn: 0.06 mass%, Al: 0.024 mass% and N: 0.0080 mass% is reheated to 1400 ° C, and then hot. After rolling to a sheet thickness of 2.2 mm and hot-rolled sheet annealing at 1100 ° C. for 60 seconds, cold-rolled to a sheet thickness of 1.5 mm and after intermediate annealing at 1120 ° C. for 80 seconds A cold rolled sheet having a final sheet thickness of 0.23 mm was obtained by the second cold rolling.
Here, the second cold rolling (final cold rolling) was 6 passes, and rolling was performed according to the pass schedule shown in Table 1. Further, before rolling in the second pass and the fifth pass, an aging treatment is performed in which the steel sheet is heated to various temperatures and held for 10 minutes, and before rolling in the first pass, the third pass, and the fourth pass, 100 ° C. And an aging treatment for 10 minutes. Further, the biting temperature (steel plate temperature at the time of biting) was 180 ° C. only in the fifth pass, and the plate was passed after cooling to 100 ° C. or lower in the other passes.
次いで、上記冷間圧延板を、５００〜７００℃間における平均昇温速度を１００℃／ｓとして７００℃まで加熱し、その後、酸化ポテンシャルＰＨ２Ｏ／ＰＨ２＝０．４０の水素と窒素の混合湿潤雰囲気中で８５０℃×１２０秒間均熱保持する脱炭焼鈍を兼ねた一次再結晶焼鈍を施した後、試験片表面にＭｇＯを主体とする焼鈍分離材を塗布し、１１５０℃で５時間保持する仕上焼鈍を施した。
斯くして得た仕上焼鈍後の試験片について、ＪＩＳ Ｃ２５５０に準拠して磁束密度１．７Ｔ、励磁周波数５０Ｈｚにおける鉄損Ｗ１７／５０、および、励磁磁場８００Ａ／ｍ、励磁周波数５０Ｈｚにおける磁束密度Ｂ８を測定した。
Next, the cold-rolled sheet is heated to 700 ° C. with an average rate of temperature increase between 500 ° C. and 700 ° C. being 100 ° C./s, and then mixed with hydrogen and nitrogen with an oxidation potential of P H2O / P H2 = 0.40. After performing primary recrystallization annealing, which also serves as decarburization annealing that keeps soaking at 850 ° C for 120 seconds in a humid atmosphere, an annealing separator mainly composed of MgO is applied to the surface of the test piece and held at 1150 ° C for 5 hours Finish annealing was performed.
About the test piece after finish annealing thus obtained, the magnetic flux density 1.7T, the iron loss W 17/50 at an excitation frequency of 50 Hz, and the magnetic flux density at an excitation magnetic field of 800 A / m and an excitation frequency of 50 Hz in accordance with JIS C2550. the B 8 were measured.
上記の実験で得られた結果について、５パス目前の時効処理温度を２６０℃に固定して、２パス目前の時効処理温度を変化させたときの鉄損Ｗ１７／５０と磁束密度Ｂ８の変化を図１に示した。この図から、２パス目前の時効処理温度を室温付近から順次高くしていくと、磁束密度も向上するが、鉄損が大きく改善され、特に時効処理温度が１５０〜２５０℃の範囲で良好な鉄損が得られていることがわかる。そして、上記の良好な鉄損を示した温度で時効処理を施した鋼板は、二次再結晶粒径の微細化が確認されることから、鉄損特性向上の主要因は、異常渦電流損の低減によるものと考えられる。 Regarding the results obtained in the above experiment, the iron loss W 17/50 and the magnetic flux density B 8 when the aging treatment temperature before the second pass was fixed at 260 ° C. and the aging treatment temperature before the second pass was changed were as follows . The change is shown in FIG. From this figure, when the aging treatment temperature before the second pass is gradually increased from around room temperature, the magnetic flux density is also improved, but the iron loss is greatly improved, particularly in the range of 150 to 250 ° C. It can be seen that iron loss is obtained. And the steel plate that has been subjected to the aging treatment at the temperature showing the above good iron loss is confirmed to be refined in the secondary recrystallized grain size. This is thought to be due to the reduction of
次に、２パス目前の時効処理温度を２００℃に固定して、５パス目前の時効処理温度を変化させたときの鉄損Ｗ１７／５０と磁束密度Ｂ８の変化を図２に示した。この図から、５パス目前の時効処理温度を高くしていくと、磁束密度が向上し、それに伴って鉄損も改善されており、特に時効処理温度が２５０〜３００℃の範囲で最も鉄損と磁束密度が良好となることがわかる。したがって、最終冷間圧延における後半パスの時効処理温度を適切に制御することで、鉄損だけでなく磁束密度をも向上できることがわかる。 Next, FIG. 2 shows changes in the iron loss W 17/50 and the magnetic flux density B 8 when the aging treatment temperature before the second pass is fixed at 200 ° C. and the aging treatment temperature before the fifth pass is changed. . From this figure, when the aging treatment temperature before the fifth pass is increased, the magnetic flux density is improved, and the iron loss is improved accordingly. Especially, the iron loss is most in the range of 250 to 300 ° C. It can be seen that the magnetic flux density is good. Therefore, it can be seen that not only the iron loss but also the magnetic flux density can be improved by appropriately controlling the aging treatment temperature of the latter half pass in the final cold rolling.
以上の実験結果から、最終冷間圧延における複数のパスを、前半パスと後半パスとに分け、それぞれの段階のパスにおいて最適な条件で時効処理を施すことで、二次再結晶粒を微細化し、磁束密度と鉄損の向上を同時に達成できることがわかった。 Based on the above experimental results, the secondary recrystallized grains were refined by dividing the multiple passes in the final cold rolling into a first half pass and a second half pass, and applying an aging treatment under the optimum conditions at each stage pass. It was found that the magnetic flux density and the iron loss can be improved at the same time.
上記の理由については、まだ十分に明らかになっていないが、発明者らは以下のように考えている。
冷間圧延後のＧｏｓｓ核は、圧延中に形成された剪断帯に形成される。剪断帯は、総圧下率が高くなった冷間圧延の後半で形成されるが、冷間圧延の前半から温間圧延して転位を固着することで、冷間圧延の後半での剪断帯の形成が促進され、Ｇｏｓｓ核が増大する。一方、冷間圧延の後半においても剪断帯を確実に形成するためには、温間圧延が必要となるが、発明者らの調査によれば、温間圧延の採用によって、ＮＤ／／＜４１１＞方位核の形成も促されることがわかった。
Although the reason for the above has not been clarified yet, the inventors consider as follows.
Goss nuclei after cold rolling are formed in shear bands formed during rolling. The shear band is formed in the latter half of the cold rolling when the total rolling reduction is high, but the shear band in the latter half of the cold rolling is fixed by warm rolling from the first half of the cold rolling and fixing the dislocation. Formation is promoted and Goss nuclei increase. On the other hand, in order to reliably form a shear band even in the latter half of the cold rolling, warm rolling is required. However, according to the investigation by the inventors, by adopting warm rolling, ND // <411. > It was found that the formation of orientation nuclei was also promoted.
ＮＤ／／＜１１１＞方位が増大する理由は、Imamuraらの報告（Metall.Mater.Trans.A.,Vol.32A,pp.403-408）に記載されているSlip plane matching理論、すなわち、隣接粒と辷り面を共通する辷り系において、たとえ、Schmid因子が最大でなくても、隣接粒と辷り面を共通する辷り系が優先的に活動することで変形帯が形成され、変形体内部で結晶回転がおこり、続く一次再結晶焼鈍において再結晶の核となるという考えによって説明できる。すなわち、Slip plane matchingで形成される変形帯の内部にＮＤ／／＜４１１＞方位の核が存在するが、上記変形帯の形成が主に冷間圧延の後半で起こるため、冷間圧延後半での時効処理が必要となる。また、Slip plane matchingによるＮＤ／／＜４１１＞方位核の形成と、剪断帯の形成によるＧｏｓｓ方位核の発生は、冷間圧延の後半の段階では互いに競合あるいは併存することが推定されるが、温間圧延としては比較的高温の２５０℃以上とすることで、Slip plane matching機構が優先的に働くようになり、ＮＤ／／＜４１１＞方位が増大したものと考えられる。 The reason why the ND // <111> orientation is increased is that the slip plane matching theory described in the report of Imamura et al. (Metall. Mater. Trans. A., Vol. 32A, pp. 403-408), ie, adjacent Even if the Schmid factor is not the maximum, the deformation band is formed by the preferential activity of the grooving system that shares the grooving surface with the adjacent grains. This can be explained by the idea that crystal rotation occurs and becomes the core of recrystallization in the subsequent primary recrystallization annealing. That is, ND // <411> oriented nuclei exist inside the deformation zone formed by Slip plane matching, but since the formation of the deformation zone occurs mainly in the latter half of the cold rolling, Aging treatment is required. In addition, it is estimated that the formation of ND // <411> orientation nuclei by Slip plane matching and the generation of Goss orientation nuclei by the formation of shear bands compete with each other or coexist in the latter half of cold rolling. It is considered that the warm plane is set to a relatively high temperature of 250 ° C. or higher so that the slip plane matching mechanism works preferentially and the ND // <411> orientation is increased.
上記の理由から、時効処理を冷間圧延の前半のみあるいは冷間圧延の後半のみでしか行わない場合には、温間圧延の効果を十分に得ることができない。そこで、本発明では、総圧下率６０％を境として、それよりも総圧下率が低い前半パスと、それよりも総圧下率が高い後半パスの両方で時効処理を施すことを必須の要件とする。
また、上記時効処理の効果を十分に得るためには、時効処理後の圧延（パス）は、圧下率を２０％以上として行うことが必要である。
For the above reasons, when the aging treatment is performed only in the first half of the cold rolling or only in the second half of the cold rolling, the effect of the warm rolling cannot be sufficiently obtained. Therefore, in the present invention, it is an indispensable requirement to perform aging treatment in both the first half pass where the total reduction rate is lower and the latter half pass where the total reduction rate is higher than that at the total reduction rate of 60%. To do.
Further, in order to sufficiently obtain the effect of the aging treatment, the rolling (pass) after the aging treatment needs to be performed at a rolling reduction of 20% or more.
さらに、冷間圧延の前半パス、後半パスそれぞれの時効処理温度には適正温度が存在し、冷間圧延前半の時効処理温度は１５０〜２５０℃の範囲、冷間圧延後半の時効処理温度は２５０〜３００℃の範囲とすることが必要である。冷間圧延前半の時効処理温度が１５０℃未満ではＧｏｓｓ方位核の形成が不十分となり、２５０℃を超えると、Ｇｏｓｓ方位核の形成は促進されるものの、ＮＤ／／＜４１１＞方位核が減少し良好な磁束密度を得ることができなくなる。一方、冷間圧延後半の時効処理温度が２５０℃未満では、ＮＤ／／＜４１１＞方位粒の形成が不十分となり、３００℃を超えると歪の回復が始まってしまうため、温間圧延の効果を十分に得ることができなくなる。 Further, there is an appropriate temperature for the aging treatment temperature in each of the first half pass and the second half pass of cold rolling, the aging treatment temperature in the first half of cold rolling is in the range of 150 to 250 ° C., and the aging treatment temperature in the second half of cold rolling is 250. It is necessary to make it into the range of -300 degreeC. When the aging treatment temperature in the first half of the cold rolling is less than 150 ° C., the formation of Goss orientation nuclei becomes insufficient. When the temperature exceeds 250 ° C., formation of Goss orientation nuclei is promoted, but ND // <411> orientation nuclei decrease. As a result, a good magnetic flux density cannot be obtained. On the other hand, if the aging treatment temperature in the latter half of the cold rolling is less than 250 ° C., the formation of ND // <411> oriented grains becomes insufficient, and if the aging treatment temperature exceeds 300 ° C., strain recovery starts. Can not get enough.
また、冷間圧延後半の時効処理後の圧延（パス）では、動的時効効果によるＧｏｓｓ方位の形成を促進するため、噛込温度を１５０℃以上にすることが必要である。なお、噛込温度は、加工発熱による過度の時効温度の上昇を防止するため、上限は３００℃程度とするのが好ましい。
本発明は、上記の新規な知見に基き、開発したものである。
Further, in the rolling (pass) after the aging treatment in the second half of the cold rolling, it is necessary to set the biting temperature to 150 ° C. or higher in order to promote the formation of the Goss orientation due to the dynamic aging effect. The upper limit of the biting temperature is preferably about 300 ° C. in order to prevent an excessive increase in aging temperature due to heat generated by processing.
The present invention has been developed based on the above novel findings.
次に、本発明の方向性電磁鋼板の製造に用いる鋼素材（スラブ）の成分組成について説明する。
Ｃ：０．００２〜０．１０ｍａｓｓ％
Ｃは、Ｇｏｓｓ方位結晶粒を発生させるのに必要な成分であり、斯かる効果を発現させるためには、０．００２ｍａｓｓ％以上含有させる必要がある。しかし、Ｃ含有量が０．１０ｍａｓｓ％を超えると、脱炭焼鈍を施しても脱炭不足となり、磁気時効を引き起こす原因となる。よって、Ｃは、０．００２〜０．１０ｍａｓｓ%の範囲とする。好ましくは０．０１〜０．０８ｍａｓｓ％の範囲である。
Next, the component composition of the steel material (slab) used for manufacture of the grain-oriented electrical steel sheet of the present invention will be described.
C: 0.002-0.10 mass%
C is a component necessary for generating Goss-oriented crystal grains. In order to exhibit such an effect, it is necessary to contain 0.002 mass% or more. However, when the C content exceeds 0.10 mass%, decarburization annealing is insufficient even if decarburization annealing is performed, causing magnetic aging. Therefore, C is in the range of 0.002 to 0.10 mass%. Preferably it is the range of 0.01-0.08 mass%.
Ｓｉ：２．５〜６．０ｍａｓｓ％
Ｓｉは、鋼の比抵抗を高め、鉄損を低減するのに必要な元素である。２．５ｍａｓｓ％未満では上記効果が十分ではなく、一方、６．０ｍａｓｓ％を超えると、鋼の加工性が低下し、圧延することが困難となる。よって、Ｓｉは２．５〜６．０ｍａｓｓ％の範囲とする。好ましくは、２．９〜５．０ｍａｓｓ％の範囲である。
Si: 2.5-6.0 mass%
Si is an element necessary for increasing the specific resistance of steel and reducing iron loss. If the amount is less than 2.5 mass%, the above effect is not sufficient. On the other hand, if the amount exceeds 6.0 mass%, the workability of the steel is lowered and it becomes difficult to roll. Therefore, Si is set to a range of 2.5 to 6.0 mass%. Preferably, it is in the range of 2.9 to 5.0 mass%.
Ｍｎ：０．０１〜０．８ｍａｓｓ％
Ｍｎは、熱間加工性を改善するために必要な元素である。０．０１ｍａｓｓ％未満では、上記効果は十分ではなく、一方、０．８ｍａｓｓ％を超えると、二次再結晶後の磁束密度が低下する。よって、Ｍｎは０．０１〜０．８ｍａｓｓ％の範囲とする。好ましくは０．０５〜０．５ｍａｓｓ％の範囲である。
Mn: 0.01 to 0.8 mass%
Mn is an element necessary for improving hot workability. If it is less than 0.01 mass%, the above effect is not sufficient. On the other hand, if it exceeds 0.8 mass%, the magnetic flux density after secondary recrystallization decreases. Therefore, Mn is set to a range of 0.01 to 0.8 mass%. Preferably it is the range of 0.05-0.5 mass%.
Ａｌ：０．０１０〜０．０５０ｍａｓｓ％、Ｎ：０．００３〜０．０２０ｍａｓｓ％
ＡｌおよびＮは、ともにインヒビタ形成のために必要な元素である。ＡｌおよびＮの含有量が、上記下限値より少ないと、インヒビタ効果が十分に得られず、一方、上記上限値を超えると、ＡｌＮを固溶させる温度が高くなり過ぎ、スラブを高温加熱しても未固溶のまま残存し、磁気特性を低下させる。よって、ＡｌおよびＮの含有量は上記範囲とする。好ましくは、Ａｌ：０．０１５〜０．０４０ｍａｓｓ％、Ｎ：０．００５〜０．０１５ｍａｓｓ％の範囲である。
Al: 0.010-0.050 mass%, N: 0.003-0.020 mass%
Both Al and N are elements necessary for inhibitor formation. If the content of Al and N is less than the above lower limit value, the inhibitor effect cannot be sufficiently obtained. On the other hand, if the content exceeds the upper limit value, the temperature for dissolving AlN becomes too high, and the slab is heated at a high temperature. Also remains undissolved and deteriorates the magnetic properties. Therefore, the contents of Al and N are within the above range. Preferably, Al: 0.015-0.040 mass%, N: 0.005-0.015 mass%.
なお、本発明に用いる鋼素材（スラブ）は、インヒビタ形成元素として、上記Ａｌ、Ｎに加えてさらに、Ｓ：０．００２〜０．０３ｍａｓｓ％および／またはＳｅ：０．００２〜０．０３ｍａｓｓ％を含有することができる。それぞれの含有量が、上記下限値より少ないと、インヒビタ効果が十分に得られず、一方、上記上限値を超えると、インヒビタｗの固溶温度が高くなり過ぎ、スラブを高温に再加熱しても未固溶で残存し、磁気特性を低下させる。よって、ＳおよびＳｅの含有量は上記範囲とするのが好ましい。より好ましくは、Ｓ：０．００５〜０．０２ｍａｓｓ％、Ｓｅ：０．０１〜０．０２ｍａｓｓ％の範囲である。 Note that the steel material (slab) used in the present invention is an inhibitor forming element, in addition to the above Al and N, further S: 0.002-0.03 mass% and / or Se: 0.002-0.03 mass%. Can be contained. If the respective contents are less than the above lower limit value, the inhibitor effect cannot be sufficiently obtained. On the other hand, if the above upper limit value is exceeded, the solid solution temperature of the inhibitor w becomes too high, and the slab is reheated to a high temperature. Also remain undissolved and degrade the magnetic properties. Therefore, the content of S and Se is preferably within the above range. More preferably, it is the range of S: 0.005-0.02mass%, Se: 0.01-0.02mass%.
また、本発明に用いる鋼素材は、上記成分組成に加えてさらに、鉄損を低減する目的で、Ｃｒ：０．０１〜０．５０ｍａｓｓ％、Ｃｕ：０．０１〜０．５０ｍａｓｓ％およびＰ：０．００５〜０．５０ｍａｓｓ％のうちから選ばれる１種または２種以上を、また、磁束密度を向上する目的で、Ｎｉ：０．０１〜１．５０ｍａｓｓ％、Ｓｂ：０．００５〜０．５０ｍａｓｓ％、Ｓｎ：０．００５〜０．５０ｍａｓｓ％、Ｍｏ：０．００５〜０．１００ｍａｓｓ％、Ｂ：０．０００２〜０．００２５ｍａｓｓ％、Ｎｂ：０．００１０〜０．０１００ｍａｓｓ％およびＶ：０．００１〜０．０１ｍａｓｓ％のうちから選ばれる１種または２種以上を含有していてもよい。それぞれの元素の含有量が上記下限値より少ないと磁気特性の向上効果が小さく、一方、上記上限値を超えると、二次再結晶が不安定化して二次再結晶粒の成長が抑制され、磁気特性が却って低下してしまう。 Moreover, the steel raw material used for this invention is Cr: 0.01-0.50mass%, Cu: 0.01-0.50mass%, and P: for the purpose of reducing an iron loss further in addition to the said component composition. For the purpose of improving the magnetic flux density, one or more selected from 0.005 to 0.50 mass%, and Ni: 0.01 to 1.50 mass%, Sb: 0.005 to 0.00. 50 mass%, Sn: 0.005-0.50 mass%, Mo: 0.005-0.100 mass%, B: 0.0002-0.0025 mass%, Nb: 0.0010-0.0100 mass%, and V: 0 One or two or more selected from 0.001 to 0.01 mass% may be contained. When the content of each element is less than the lower limit, the effect of improving the magnetic properties is small, whereas when the upper limit is exceeded, secondary recrystallization is destabilized and the growth of secondary recrystallized grains is suppressed, On the other hand, the magnetic properties are degraded.
上記成分以外の残部は、Ｆｅおよび不可避的不純物である。ただし、本発明の効果を害しない範囲内であれば、上記以外の成分の含有を拒むものではない。 The balance other than the above components is Fe and inevitable impurities. However, as long as the effects of the present invention are not impaired, the inclusion of components other than those described above is not rejected.
次に、本発明の方向性電磁鋼板の製造方法について説明する。
本発明の方向性電磁鋼板の製造方法に用いる鋼素材（スラブ）は、上記成分組成を有する鋼を、通常公知の精錬プロセスで溶製した後、連続鋳造法または造塊−分塊圧延法で製造することができるが、成分組成の均一性が良好な連続鋳造法で製造するのが好ましい。
Next, the manufacturing method of the grain-oriented electrical steel sheet of this invention is demonstrated.
The steel material (slab) used in the method for producing a grain-oriented electrical steel sheet according to the present invention is obtained by melting a steel having the above component composition by a generally known refining process, and then performing continuous casting or ingot-bundling rolling. Although it can manufacture, it is preferable to manufacture by the continuous casting method with the favorable uniformity of a component composition.
上記スラブは、インヒビタ形成成分を十分に固溶させるため、１４００℃程度の温度に再加熱した後、常法の条件で熱間圧延し、熱延板とする。 In order to sufficiently dissolve the inhibitor-forming component, the slab is reheated to a temperature of about 1400 ° C., and then hot-rolled under ordinary conditions to obtain a hot-rolled sheet.
上記熱延板は、良好な磁気特性を得るため、熱延板焼鈍を施すことが必要である。この熱延板焼鈍の温度は、８００〜１１５０℃の範囲とするのが好ましい。８００℃未満では、熱延で形成されたバンド組織が残留し、整粒の一次再結晶組織を得ることが難しくなって二次再結晶の発達が阻害される。一方、１１５０℃を超えると、熱延板焼鈍後の結晶粒が粗大化し過ぎて、やはり、整粒の一次再結晶組織を得ることが難しくなるからである。 The hot-rolled sheet needs to be subjected to hot-rolled sheet annealing in order to obtain good magnetic properties. The temperature of this hot-rolled sheet annealing is preferably in the range of 800 to 1150 ° C. If it is less than 800 degreeC, the band structure formed by hot rolling will remain, it will become difficult to obtain the primary recrystallized structure of a sized particle, and the development of secondary recrystallization will be inhibited. On the other hand, when the temperature exceeds 1150 ° C., the crystal grains after the hot-rolled sheet annealing are excessively coarsened, so that it becomes difficult to obtain a primary recrystallized structure of sized grains.
上記熱延板焼鈍後の鋼板は、その後、１回または中間焼鈍を挟む２回以上の冷間圧延を行い最終板厚の冷延板とする。上記中間焼鈍を行う場合の焼鈍温度は、９００〜１２００℃の範囲とするのが好ましい。９００℃未満では、再結晶粒が微細化して、一次再結晶組織におけるＧｏｓｓ方位核が減少し、磁気特性の低下を招く。一方、１２００℃を超えると、熱延板焼鈍と同様、結晶粒が粗大化し過ぎて、整粒の一次再結晶組織を得ることが難しくなるからである。 The steel sheet after the hot-rolled sheet annealing is then cold-rolled with a final thickness by performing cold rolling twice or more times with one or intermediate annealing. The annealing temperature when performing the intermediate annealing is preferably in the range of 900 to 1200 ° C. If it is less than 900 ° C., the recrystallized grains become finer, the Goss orientation nuclei in the primary recrystallized structure are reduced, and the magnetic properties are deteriorated. On the other hand, when the temperature exceeds 1200 ° C., the crystal grains become too coarse as in the hot-rolled sheet annealing, and it becomes difficult to obtain a primary recrystallized structure of the sized grains.
また、最終板厚まで圧延する最終冷間圧延は、一次再結晶集合組織のＮＤ／／＜１１１＞組織およびＮＤ／／＜４１１＞組織を増やして良好な磁束密度を得るため、総圧下率を８０〜９５％の範囲とする必要がある。総圧下率が８０％未満では、一次再結晶集合組織のＮＤ／／＜１１１＞組織およびＮＤ／／＜４１１＞組織が十分に先鋭化されないため、高い磁束密度が得られず、一方、総圧下率が９５％を超えると、二次再結晶が起こり難くなるからである。好ましい総圧下率は８５〜９２％の範囲である。 In addition, the final cold rolling for rolling to the final plate thickness increases the ND // <111> structure and the ND // <411> structure of the primary recrystallization texture to obtain a good magnetic flux density. It is necessary to make it 80 to 95% of range. If the total rolling reduction is less than 80%, the ND // <111> structure and ND // <411> structure of the primary recrystallization texture are not sufficiently sharpened, so that a high magnetic flux density cannot be obtained. This is because when the rate exceeds 95%, secondary recrystallization hardly occurs. A preferred total rolling reduction is in the range of 85-92%.
また、上記最終冷間圧延は、総圧下率が６０％未満の範囲で、少なくとも１パスは、１５０〜２５０℃の温度で１分以上保持する時効処理を施した後、２０％以上の圧下率で圧延を行うことが必要である。時効処理をまったく行わないか、時効処理温度が１５０℃未満あるいは時効時間が１分未満では、冷間圧延後のＧｏｓｓ方位核が十分に形成されず、二次再結晶粒微細化による鉄損改善効果が十分に得られない。一方、時効処理温度が２５０℃より高いと、Ｇｏｓｓ方位核の形成は促進されるものの、ＮＤ／／＜４１１＞方位核が減少し、良好な磁束密度を得ることができなくなる。 In the final cold rolling, the total rolling reduction is in the range of less than 60%, and at least one pass is subjected to an aging treatment at a temperature of 150 to 250 ° C. for 1 minute or more, and then the rolling reduction of 20% or more. It is necessary to carry out rolling. If the aging treatment is not performed at all, or if the aging treatment temperature is less than 150 ° C. or the aging time is less than 1 minute, the Goss orientation nucleus after cold rolling is not sufficiently formed, and iron loss is improved by refining secondary recrystallized grains. The effect cannot be obtained sufficiently. On the other hand, when the aging treatment temperature is higher than 250 ° C., formation of Goss orientation nuclei is promoted, but ND // <411> orientation nuclei are reduced, and a good magnetic flux density cannot be obtained.
また、上記時効処理直後のパスの圧下率が２０％より低いと、時効処理による集合組織改善効果を十分に得ることができず、二次再結晶粒の微細化と良好な磁束密度がともに得られない。なお、上記の時効処理は、好ましくは１７０〜２３０℃の温度範囲で５分以上保持するのが好ましく、時効処理後のパスの圧下率は２５〜５０％の範囲とするのが好ましい。 Also, if the pass reduction ratio immediately after the aging treatment is lower than 20%, the effect of improving the texture by the aging treatment cannot be sufficiently obtained, and both the refinement of secondary recrystallized grains and a good magnetic flux density are obtained. I can't. In addition, it is preferable to hold | maintain said aging treatment in the temperature range of 170-230 degreeC for 5 minutes or more preferably, and it is preferable to make the rolling reduction of the pass after an aging treatment into the range of 25-50%.
さらに、上記最終冷間圧延の総圧下率が６０％以上の範囲でも、少なくとも１パスは、２５０〜３００℃の温度で１分以上保持する時効処理を施した後、噛込温度を１５０℃以上として２０％以上の圧下率で圧延することが必要である。時効処理を行わないか、時効処理温度が１５０℃未満あるいは処理温度が１分未満では、冷間圧延後のＧｏｓｓ方位核およびＮＤ／／＜４１１＞組織が十分に発達せず、二次再結晶粒の微細化と、高磁束密度を実現することができない。一方、時効処理温度が３００℃を超えると、回復が進行するため、温間圧延の効果が得られなくなる。 Furthermore, even when the total rolling reduction of the final cold rolling is in the range of 60% or more, at least one pass is subjected to an aging treatment for holding for 1 minute or more at a temperature of 250 to 300 ° C, and then the biting temperature is 150 ° C or more. It is necessary to perform rolling at a rolling reduction of 20% or more. If the aging treatment is not performed or the aging treatment temperature is less than 150 ° C. or the treatment temperature is less than 1 minute, the Goss orientation nucleus and the ND // <411> structure after cold rolling are not sufficiently developed, and secondary recrystallization is performed. Grain refinement and high magnetic flux density cannot be realized. On the other hand, when the aging treatment temperature exceeds 300 ° C., recovery proceeds, so that the effect of warm rolling cannot be obtained.
また、上記時効処理直後のパスは、噛込温度が１５０℃未満であると、動的時効によるＧｏｓｓ方位核が十分に形成されず、また、圧下率が２０％より低いと時効処理による集合組織改善効果を十分に得ることができないため、二次再結晶粒の微細化と良好な磁束密度がともに得られない。なお、上記の時効処理は、好ましくは２７０〜３００℃の温度で５分以上保持するのが好ましく、時効処理直後のパスは、噛込温度を１７０℃以上とし、圧下率は２５〜５０％の範囲とするのが好ましい。 Further, in the pass immediately after the aging treatment, if the biting temperature is less than 150 ° C., the Goss orientation nucleus due to dynamic aging is not sufficiently formed, and if the rolling reduction is lower than 20%, the texture by the aging treatment Since the improvement effect cannot be obtained sufficiently, neither the refinement of secondary recrystallized grains nor a good magnetic flux density can be obtained. The above aging treatment is preferably held at a temperature of 270 to 300 ° C. for 5 minutes or more, and the pass immediately after the aging treatment has a biting temperature of 170 ° C. or more and a rolling reduction of 25 to 50%. The range is preferable.
なお、本発明の最終冷間圧延は、最低でも２回の時効処理を施すことが必要であることから、２パス以上の複数パスで圧延することが必要である。上限の圧延回数は、特に限定されないが、上記時効処理後の圧延で必要な圧下率（２０％以上）を確保し、かつ、高い生産性を確保する観点から、８パス以下に止めるのが好ましい。 In addition, since the final cold rolling of this invention needs to give an aging treatment twice at least, it is necessary to roll by two or more passes. The upper limit number of rolling is not particularly limited, but it is preferable to stop at 8 passes or less from the viewpoint of securing a reduction ratio (20% or more) necessary for rolling after the aging treatment and ensuring high productivity. .
上記最終冷間圧延を行う圧延機は、タンデム圧延機、リバース圧延機のどちらでもよいが、パス間で１分以上の時効処理が必要となることから、リバース圧延機で行うのが好ましい。さらに、上記時効処理を施す方法は、上記した時効条件（温度、時間）を確保することができれば、いずれの方法でもよく、例えば、１パス目前の時効処理以外であれば、圧延による加工発熱を利用してもよいし、ヒーター加熱や誘導加熱によって鋼板を所定温度に加熱後、コイルに巻き取って上記温度、時間に保持したり、圧延後の鋼板をコイルに巻き取り後、加熱炉を用いて加熱したりする方法を用いてもよい。 The rolling mill for performing the final cold rolling may be either a tandem rolling mill or a reverse rolling mill. However, since a aging treatment of 1 minute or more is required between passes, it is preferably performed by a reverse rolling mill. Furthermore, the method for performing the aging treatment may be any method as long as the aging conditions (temperature, time) described above can be ensured. For example, if the aging treatment is not performed before the first pass, the processing heat generated by rolling is generated. It may be used, and after heating the steel plate to a predetermined temperature by heater heating or induction heating, it is wound around a coil and held at the above temperature and time, or the rolled steel plate is wound around the coil and then a heating furnace is used. Alternatively, a heating method may be used.
最終板厚に圧延した冷延板は、その後、均熱温度を７００〜９００℃とする一次再結晶焼鈍を施す。この際、上記一次再結晶焼鈍の加熱過程では、良好な磁気特性を得るために５００〜７００℃間における平均昇温速度を５０℃／ｓ以上とする必要がある。上記昇温速度が５０℃／ｓ未満では、Ｇｏｓｓ方位核とＮＤ／／＜４１１＞方位核の再結晶が促進されず、二次再結晶粒の微細化と、高磁束密度化を実現することができない。好ましい昇温速度は１００℃／ｓ以上である。なお、昇温速度の上限は特に制限しないが、昇温速度の制御性の観点から、６００℃／ｓ程度とするのが好ましい。 The cold-rolled sheet rolled to the final sheet thickness is then subjected to primary recrystallization annealing with a soaking temperature of 700 to 900 ° C. Under the present circumstances, in the heating process of the said primary recrystallization annealing, in order to acquire a favorable magnetic characteristic, it is necessary to make the average temperature increase rate between 500-700 degreeC into 50 degrees C / s or more. When the heating rate is less than 50 ° C./s, recrystallization of Goss orientation nuclei and ND // <411> orientation nuclei is not promoted, and secondary recrystallized grains are refined and magnetic flux density is increased. I can't. A preferable temperature increase rate is 100 ° C./s or more. The upper limit of the temperature increase rate is not particularly limited, but is preferably about 600 ° C./s from the viewpoint of controllability of the temperature increase rate.
なお、本発明の方向性電磁鋼板の製造方法に用いる鋼素材は、Ｃを０．００２ｍａｓｓ％以上含有することを必須の要件としているが、Ｃが製品板中に０．００５ｍａｓｓ％を超えて残留していると、磁気時効を起こして磁気特性が低下するため、脱炭焼鈍を施して、Ｃを低減する必要がある。この脱炭焼鈍は、水素−窒素混合の湿潤雰囲気下で、７００〜９００℃の温度で行うことが望ましく、一次再結晶焼鈍の均熱処理と兼ねて行ってもよいし、一次再結晶焼鈍とは別の工程として行ってもよい。 In addition, although the steel raw material used for the manufacturing method of the grain-oriented electrical steel sheet according to the present invention has an essential requirement to contain C in an amount of 0.002 mass% or more, C remains in the product plate in excess of 0.005 mass%. If this is the case, magnetic aging is caused and the magnetic properties are deteriorated. Therefore, it is necessary to perform decarburization annealing to reduce C. This decarburization annealing is desirably performed at a temperature of 700 to 900 ° C. in a wet atmosphere of a hydrogen-nitrogen mixture, and may be performed in combination with the soaking process of the primary recrystallization annealing. What is primary recrystallization annealing? You may carry out as another process.
上記脱炭焼鈍後の鋼板は、その後、ＭｇＯを主体とする焼鈍分離剤を鋼板表面に塗布・乾燥した後、仕上焼鈍を施して、二次再結晶組織を発達させる。なお、鋼板表面への焼鈍分離剤の塗布は、通常、スラリーとして塗布するが、水分を持ち込まない静電塗布を用いて行ってもよい。上記仕上焼鈍は、二次再結晶を発現させるためには８００℃以上の温度で行うことが、また、二次再結晶を完了させるためには、８００℃以上の温度で２０時間以上保持することが望ましい。二次再結晶を発現させるための好ましい温度は８５０〜９５０℃の範囲である。 The steel sheet after the decarburization annealing is then applied and dried with an annealing separator mainly composed of MgO on the steel sheet surface, and then subjected to finish annealing to develop a secondary recrystallized structure. In addition, although application | coating of the annealing separation agent to a steel plate surface is normally apply | coated as a slurry, you may carry out using electrostatic application | coating which does not bring in a water | moisture content. The finish annealing is performed at a temperature of 800 ° C. or higher in order to develop secondary recrystallization, and is held at a temperature of 800 ° C. or higher for 20 hours or longer in order to complete the secondary recrystallization. Is desirable. A preferable temperature for developing secondary recrystallization is in the range of 850 to 950 ° C.
なお、打抜加工性を重視し、鋼板表面にガラス質のフォルステライト（Ｍｇ２ＳｉＯ４）被膜を形成させない場合には、二次再結晶が完了すれば十分であるので、そのまま仕上焼鈍を終了することも可能である。
一方、フォルステライト被膜を形成させたり、インヒビタ形成成分を除去する純化処理を施したりする場合には、二次再結晶完了後、水素雰囲気下で、さらに１２００℃程度の温度まで加熱することが好ましい。
If emphasis is placed on the punching workability and the glassy forsterite (Mg 2 SiO 4 ) film is not formed on the steel plate surface, it is sufficient that the secondary recrystallization is completed, so the finish annealing is finished as it is. It is also possible to do.
On the other hand, when a forsterite film is formed or a purification treatment is performed to remove the inhibitor-forming component, it is preferable to heat to a temperature of about 1200 ° C. in a hydrogen atmosphere after the completion of secondary recrystallization. .
上記仕上焼鈍後の鋼板は、その後、水洗やブラッシング、酸洗等で、鋼板表面に残留した未反応の焼鈍分離剤を除去した後、平坦化焼鈍を行って形状を矯正するのが鉄損低減のためには有効である。
なお、上記仕上焼鈍後の鋼板は、積層して使用する場合には、絶縁性を付与するため、上記平坦化焼鈍の前または後で、あるいは上記平坦化焼鈍時に、鋼板表面に絶縁被膜を被成することが好ましい。
また、上記絶縁被膜は、鉄損をより低減するためには、鋼鈑表面に張力を付与する張力付与型のものであることが好ましい。上記張力付与被膜の被成に際しては、バインダーを介して被膜を塗布する方法や、物理蒸着法や化学蒸着法により無機物を鋼板表層に蒸着させてから被膜を塗布する方法を採用すると、被膜密着性に優れかつ著しい鉄損低減効果を有する被膜が得られるのでより好ましい。
After the finish annealing, the steel loss is reduced by removing the unreacted annealing separator remaining on the steel sheet surface by washing, brushing, pickling, etc., and then performing flattening annealing to correct the shape. It is effective for.
In addition, when the steel sheet after the finish annealing is used by being laminated, an insulating film is applied to the steel sheet surface before or after the flattening annealing or at the time of the flattening annealing in order to provide insulation. Preferably.
The insulating coating is preferably of a tension imparting type that imparts tension to the surface of the steel plate in order to further reduce iron loss. When applying the above tension-imparting film, the film adhesion can be achieved by applying a film through a binder or by applying a film after depositing an inorganic substance on the steel sheet surface by physical vapor deposition or chemical vapor deposition. It is more preferable because a coating film having excellent iron loss reduction effect can be obtained.
さらに、製品鋼板の鉄損をより低減するためには、磁区細分化処理を施すことが好ましい。磁区細分化処理を施す方法としては、従来から公知の、製品鋼板にローラ加工等で線状の溝や歪領域を形成したりする方法や、電子ビームやレーザ、プラズマジェットなどを照射して線状の熱歪領域や衝撃歪領域を導入したりする方法、あるいは、最終板厚とした冷延板の表面に、エッチング加工等で溝を形成したりする方法等を用いることができる。 Furthermore, in order to further reduce the iron loss of the product steel plate, it is preferable to perform a magnetic domain refinement treatment. As a method for performing magnetic domain subdivision treatment, there are conventionally known methods such as forming a linear groove or strain region on a product steel plate by roller processing or the like, or irradiating an electron beam, laser, plasma jet, etc. Or a method of introducing grooves on the surface of the cold-rolled sheet having the final thickness by etching or the like.
Ｃ：０．０７ｍａｓｓ％、Ｓｉ：３．４ｍａｓｓ％、Ｍｎ：０．１０ｍａｓｓ％、Ａｌ：０．０２３ｍａｓｓ％およびＮ：０．００８ｍａｓｓ％を含有する鋼スラブを１４００℃に再加熱した後、熱間圧延して２．２ｍｍの板厚の熱延板とし、１１００℃×６０秒の熱延板焼鈍を施した後、冷間圧延して板厚１．８ｍｍとし、１１２０℃×６０秒の中間焼鈍を施した後、２回目の冷間圧延で０．２３ｍｍの最終板厚の冷延板とした。
上記２回目の冷間圧延（最終冷間圧延）は、リバースミルで、表２に示す７パスのパススケジュールで圧延した。この際、最終冷間圧延の３パス目と６パス目の圧延前に、加熱温度を種々に変えて１５分間保持する時効処理を施し、その他のパスの前では、１００℃で１５分間の時効処理を施した。また、噛込温度は、５パス目のみを１２０℃または１８０℃に変化させ、それ以外のパスでは１００℃以下に冷却した。
次いで、上記冷延板を、５００〜７００℃間の平均昇温速度を２０℃／ｓまたは８０℃／ｓに変えて７００℃まで加熱した後、酸化ポテンシャルＰＨ２Ｏ／ＰＨ２＝０．３９の水素と窒素の混合湿潤雰囲気下での８５０℃×１２０秒の脱炭焼鈍を兼ねた一次再結晶焼鈍を施した後、試験片表面にＭｇＯを主体とする焼鈍分離材を塗布し、１２００℃で５時間保持する仕上焼鈍を施した。
斯くして得た仕上焼鈍後の試験片について、ＪＩＳ Ｃ２５５０に準拠して磁束密度１．７Ｔ、励磁周波数５０Ｈｚにおける鉄損Ｗ１７／５０、および励磁磁場８００Ａ／ｍ、励磁周波数５０Ｈｚにおける磁束密度Ｂ８を測定し、その結果を表３に示した。表３から、３パス前の時効処理温度を１５０〜２５０℃の範囲、６パス前の時効処理温度を２５０〜３００℃の範囲とし、かつ、６パス目の噛込温度を１５０℃以上とすることで、磁束密度と鉄損が大きく改善されていることがわかる。また、一次再結晶焼鈍における昇温速度を５０℃／ｓ以上に高めることで、鉄損がより改善されていることがわかる。
A steel slab containing C: 0.07 mass%, Si: 3.4 mass%, Mn: 0.10 mass%, Al: 0.023 mass%, and N: 0.008 mass% is reheated to 1400 ° C and then hot. Rolled to a hot-rolled sheet with a thickness of 2.2 mm, subjected to hot-rolled sheet annealing at 1100 ° C. × 60 seconds, and then cold-rolled to a thickness of 1.8 mm, intermediate annealing at 1120 ° C. × 60 seconds After that, a cold rolled sheet having a final sheet thickness of 0.23 mm was obtained by the second cold rolling.
The second cold rolling (final cold rolling) was performed by a reverse mill with a 7-pass schedule shown in Table 2. At this time, an aging treatment is performed by changing the heating temperature for 15 minutes before rolling in the third and sixth passes of the final cold rolling, and aging for 15 minutes at 100 ° C. before the other passes. Treated. Further, the biting temperature was changed to 120 ° C. or 180 ° C. only in the fifth pass, and cooled to 100 ° C. or lower in the other passes.
Next, the cold rolled sheet was heated to 700 ° C. by changing the average temperature rising rate between 500 ° C. and 700 ° C. to 20 ° C./s or 80 ° C./s , and then the oxidation potential P H2O / P H2 = 0.39. After performing primary recrystallization annealing that also serves as decarburization annealing at 850 ° C. for 120 seconds in a mixed wet atmosphere of hydrogen and nitrogen, an annealing separator mainly composed of MgO is applied to the surface of the test piece at 1200 ° C. Finish annealing was performed for 5 hours.
About the test piece after the finish annealing thus obtained, the magnetic flux density 1.7T, the iron loss W 17/50 at an excitation frequency of 50 Hz, and the magnetic flux density B at an excitation magnetic field of 800 A / m and an excitation frequency of 50 Hz in accordance with JIS C2550. 8 was measured and the results are shown in Table 3. From Table 3, the aging treatment temperature before 3 passes is in the range of 150 to 250 ° C, the aging treatment temperature before 6 passes is in the range of 250 to 300 ° C, and the biting temperature in the 6th pass is 150 ° C or higher. This shows that the magnetic flux density and iron loss are greatly improved. Moreover, it turns out that iron loss is further improved by raising the temperature increase rate in primary recrystallization annealing to 50 degrees C / s or more.
表４に示す各種成分組成を有する鋼スラブを１４００℃に再加熱した後、熱間圧延して２．２ｍｍの板厚の熱延板とし、１１００℃×６０秒の熱延板焼鈍を施した後、冷間圧延して板厚１．８ｍｍとし、１１２０℃×６０秒の中間焼鈍を施した後、２回目の冷間圧延により最終板厚０．２３ｍｍの冷間圧延板とした。
上記２回目の冷間圧延（最終冷間圧延）は、リバースミルを用いて７パスで行い、実施例１と同じく表２に示すパススケジュールで圧延を行った。この際、上記冷間圧延の２、３、４パスのそれぞれのパス前に、２００℃で２０分間保持する時効処理を施し、さらに、５、６、７パスのそれぞれのパス前に、２７０℃で２０分間保持する時効処理を施すとともに、すべてのパスの噛込温度を１６０℃〜２００℃の範囲に制御した。
次いで、上記冷間圧延板を５００℃〜７００℃間における平均昇温速度を１２０℃／ｓとして７００℃まで加熱し、その後、酸化ポテンシャルＰＨ２Ｏ／ＰＨ２＝０．４２の水素と窒素の混合湿潤雰囲気下での８５０℃×１２０秒の脱炭焼鈍を兼ねた一次再結晶焼鈍を施した後、試験片表面にＭｇＯを主体とする焼鈍分離材を塗布し、１２００℃で５時間保持する仕上焼鈍を施した。
斯くして得た仕上げ焼鈍の試験片について、ＪＩＳ Ｃ２５５０に準拠して磁束密度１．７Ｔ、励磁周波数５０Ｈｚにおける鉄損Ｗ１７／５０、および励磁磁場８００Ａ／ｍ、励磁周波数５０Ｈｚにおける磁束密度Ｂ８を測定し、表４に併記した。表４から本発明に適合する組成成分を含有する鋼素材を用いることにより、磁束密度と鉄損に優れた方向性電磁鋼板を製造できることがわかる。
Steel slabs having various component compositions shown in Table 4 were reheated to 1400 ° C., and then hot-rolled to obtain a hot-rolled sheet having a thickness of 2.2 mm and subjected to hot-rolled sheet annealing at 1100 ° C. × 60 seconds. Thereafter, it was cold-rolled to a thickness of 1.8 mm, subjected to intermediate annealing at 1120 ° C. for 60 seconds, and then cold-rolled to a final thickness of 0.23 mm by the second cold rolling.
The second cold rolling (final cold rolling) was performed in 7 passes using a reverse mill, and the rolling was performed according to the pass schedule shown in Table 2 as in Example 1. In this case, an aging treatment is performed for 20 minutes at 200 ° C. before each of the 2, 3, and 4 passes of cold rolling, and 270 ° C. before each of the 5, 6, and 7 passes. The aging treatment was performed for 20 minutes, and the biting temperature of all passes was controlled in the range of 160 ° C to 200 ° C.
Next, the cold-rolled sheet is heated to 700 ° C. with an average rate of temperature increase between 500 ° C. and 700 ° C. being 120 ° C./s, and then mixed with hydrogen and nitrogen at an oxidation potential of P H2O / P H2 = 0.42. Finished by applying a primary recrystallization annealing that also serves as a decarburization annealing at 850 ° C. for 120 seconds in a humid atmosphere, and then applying an annealing separator mainly composed of MgO to the surface of the test piece and holding at 1200 ° C. for 5 hours. Annealed.
About the test piece of finish annealing obtained in this way, the magnetic flux density 1.7 T, the iron loss W 17/50 at an excitation frequency of 50 Hz, and the magnetic flux density B 8 at an excitation magnetic field of 800 A / m and an excitation frequency of 50 Hz in accordance with JIS C2550. Was measured and listed in Table 4. It can be seen from Table 4 that a grain-oriented electrical steel sheet excellent in magnetic flux density and iron loss can be produced by using a steel material containing a composition component suitable for the present invention.
Ｃ：０．０７ｍａｓｓ％、Ｓｉ：３．２ｍａｓｓ％、Ｍｎ：０．０９ｍａｓｓ％、Ａｌ：０．０２５ｍａｓｓ％およびＮ：０．００９ｍａｓｓ％を含有する鋼スラブを１４００℃に再加熱した後、熱間圧延して板厚２．２ｍｍの熱延板とし、１１００℃×６０秒の熱延板焼鈍を施した後、冷間圧延して板厚１．５ｍｍとし、１１００℃×６０秒の中間焼鈍を施した後、２回目の冷間圧延で最終板厚０．２３ｍｍの冷間圧延板とした。
ここで、上記２回目の冷間圧延（最終冷間圧延）はリバースミルを用いて６パスで行い、表５に示すパススケジュールで圧延を行うとともに、表６に示した２回のパスの前において、１回目は２００℃×１０分、２回目は２５０℃×１０分の時効処理を施した。また、２回目の時効処理後のパスでは噛込温度を１５０℃とし、それ以外のパスでは、８０℃で１０分間の時効処理を施した後、８０℃の温度のままで圧延を行った。
次いで、上記冷間圧延板を５００〜７００℃間の平均昇温速度を１２０℃／ｓとして７００℃まで加熱した後、酸化ポテンシャルＰＨ２Ｏ／ＰＨ２＝０．３９の水素と窒素の混合湿潤雰囲気下での８５０℃×１２０秒の脱炭焼鈍を兼ねた一次再結晶焼鈍を施した後、試験片表面にＭｇＯを主体とする焼鈍分離材を塗布し、１２００℃で５時間保持する仕上焼鈍を施した。
斯くして得た仕上焼鈍後の試験片について、ＪＩＳ Ｃ２５５０に準拠して磁束密度１．７Ｔ、励磁周波数５０Ｈｚにおける鉄損Ｗ１７／５０、および励磁磁場８００Ａ／ｍ、励磁周波数５０Ｈｚにおける磁束密度Ｂ８を測定し、その結果を表６に示した。表６から、１回目の時効処理を総圧下率が６０％未満の範囲で施し、２回目の時効処理を総圧下率が６０％以上の範囲で施すことで、磁気特性が大きく改善していることがわかる。
A steel slab containing C: 0.07 mass%, Si: 3.2 mass%, Mn: 0.09 mass%, Al: 0.025 mass%, and N: 0.009 mass% is reheated to 1400 ° C. and then hot. Rolled to a hot-rolled sheet having a thickness of 2.2 mm, subjected to hot-rolled sheet annealing at 1100 ° C. × 60 seconds, then cold-rolled to a sheet thickness of 1.5 mm, and subjected to intermediate annealing at 1100 ° C. × 60 seconds. After the application, a cold rolled sheet having a final sheet thickness of 0.23 mm was obtained by the second cold rolling.
Here, the second cold rolling (final cold rolling) is performed in 6 passes using a reverse mill, rolled in accordance with the pass schedule shown in Table 5, and before the 2 passes shown in Table 6. In the first, an aging treatment was performed at 200 ° C. × 10 minutes for the first time and 250 ° C. × 10 minutes for the second time. Further, in the pass after the second aging treatment, the biting temperature was 150 ° C., and in the other passes, the aging treatment was performed at 80 ° C. for 10 minutes, and then the rolling was performed at the temperature of 80 ° C.
Subsequently, after heating the said cold rolled sheet to 700 degreeC by making the average temperature increase rate between 500-700 degreeC into 120 degreeC / s, the mixing wet atmosphere of the oxidation potential PH2O / PH2 = 0.39. After performing primary recrystallization annealing that also serves as decarburization annealing at 850 ° C. for 120 seconds below, finish annealing is performed by applying an annealing separator mainly composed of MgO to the test piece surface and holding at 1200 ° C. for 5 hours. gave.
About the test piece after the finish annealing thus obtained, the magnetic flux density 1.7T, the iron loss W 17/50 at an excitation frequency of 50 Hz, and the magnetic flux density B at an excitation magnetic field of 800 A / m and an excitation frequency of 50 Hz in accordance with JIS C2550. 8 was measured and the result is shown in Table 6. From Table 6, the magnetic properties are greatly improved by applying the first aging treatment in a range where the total reduction ratio is less than 60% and applying the second aging treatment in a range where the total reduction ratio is 60% or more. I understand that.
Claims (3)
前記冷間圧延における最終冷間圧延を、２パス以上で総圧下率８０〜９５％で行い、かつ、
総圧下率が６０％未満の範囲で少なくとも１パスを、１５０〜２５０℃×１分以上の時効処理を施した後、２０％以上の圧下率で圧延し、
総圧下率が６０％以上の範囲で少なくとも１パスを、２５０〜３００℃×１分以上の時効処理を施した後、噛込温度を１５０℃以上として２０％以上の圧下率で圧延し、
前記一次再結晶焼鈍の加熱過程における５００〜７００℃間の平均昇温速度を５０℃／ｓ以上とすることを特徴とする方向性電磁鋼板の製造方法。 C: 0.04 to 0.10 mass%, Si: 2.5 to 6.0 mass%, Mn: 0.01 to 0.8 mass%, Al: 0.010 to 0.050 mass%, N: 0.003 A steel slab containing 0.020 mass%, the balance being Fe and inevitable impurities, is hot-rolled, hot-rolled sheet annealed, cold-rolled twice or more sandwiching intermediate or intermediate annealing, and decarburized annealing In the method for producing a grain-oriented electrical steel sheet comprising a series of steps in which the primary recrystallization annealing also serves as a coating, applying an annealing separator mainly composed of MgO to the steel sheet surface, and finishing annealing,
The final cold rolling in the cold rolling is performed at 2 or more passes with a total rolling reduction of 80 to 95%, and
At least one pass in a range where the total rolling reduction is less than 60%, after aging treatment at 150 to 250 ° C. for 1 minute or more, rolling at a rolling reduction of 20% or more,
At least one pass in a range where the total rolling reduction is 60% or more, after aging treatment of 250 to 300 ° C. × 1 minute or more, rolling at a rolling reduction of 20% or more with a biting temperature of 150 ° C. or more,
A method for producing a grain-oriented electrical steel sheet, wherein an average rate of temperature increase between 500 and 700 ° C. in the heating process of the primary recrystallization annealing is 50 ° C./s or more.
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| KR101947026B1 (en) * | 2016-12-22 | 2019-02-12 | 주식회사 포스코 | Grain oriented electrical steel sheet and method for manufacturing the same |
| CN109365525B (en) * | 2018-10-09 | 2020-06-23 | 鞍钢股份有限公司 | Method for controlling quality of cold-rolled silicon steel casting blank |
| JP6988845B2 (en) * | 2019-02-26 | 2022-01-05 | Ｊｆｅスチール株式会社 | Manufacturing method of grain-oriented electrical steel sheet |
| CN110551886A (en) * | 2019-08-07 | 2019-12-10 | 包头威丰新材料有限公司 | Oriented silicon steel annealing process |
| JP7463976B2 (en) * | 2020-02-28 | 2024-04-09 | Ｊｆｅスチール株式会社 | Manufacturing method of grain-oriented electrical steel sheet |
| JP7338511B2 (en) * | 2020-03-03 | 2023-09-05 | Ｊｆｅスチール株式会社 | Manufacturing method of grain-oriented electrical steel sheet |
| CN115916425A (en) * | 2020-06-30 | 2023-04-04 | 杰富意钢铁株式会社 | Method for producing grain-oriented electromagnetic steel sheet |
| KR20230019158A (en) * | 2020-06-30 | 2023-02-07 | 제이에프이 스틸 가부시키가이샤 | Grain-oriented electrical steel sheet manufacturing method and equipment row |
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| JPS5294825A (en) * | 1976-02-05 | 1977-08-09 | Nippon Steel Corp | Preparation of unidirectional silicon steel sheet |
| JPS6059044A (en) * | 1983-09-10 | 1985-04-05 | Nippon Steel Corp | Grain-oriented silicon steel sheet having low iron loss value and its production |
| JPH08253816A (en) * | 1995-03-15 | 1996-10-01 | Nippon Steel Corp | Production of grain oriented silicon steel sheet with ultrahigh magnetic flux density |
| JP3368409B2 (en) * | 1995-09-12 | 2003-01-20 | 新日本製鐵株式会社 | Manufacturing method of low iron loss unidirectional electrical steel sheet |
| ITRM20070218A1 (en) * | 2007-04-18 | 2008-10-19 | Ct Sviluppo Materiali Spa | PROCEDURE FOR THE PRODUCTION OF MAGNETIC SHEET WITH ORIENTED GRAIN |
| JP5684481B2 (en) * | 2010-02-15 | 2015-03-11 | 新日鐵住金株式会社 | Method for producing grain-oriented electrical steel sheet |
| JP5991484B2 (en) * | 2011-12-06 | 2016-09-14 | Ｊｆｅスチール株式会社 | Manufacturing method of low iron loss grain oriented electrical steel sheet |
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